[LSF/MM/BPF TOPIC] Dynamic allocation of pseudo file systems

[LSF/MM/BPF TOPIC] Dynamic allocation of pseudo file systems

[Steven Rostedt]

At the 2021 Linux Plumbers Tracing Microconference there was a discussionon creating just-in-time dentrys for pseudo file systems (the tracing one
was about the events directory in tracefs).

https://lpc.events/event/11/contributions/1085/attachments/855/1668/Eventfs_split_v15.pdf

https://www.youtube.com/watch?v=jsxuVI7Wav0&list=PLVsQ_xZBEyN3wA8Ej4BUjudXFbXuxhnfc&t=7561s

At the microconference there was also interest in extending this to other
pseudo file systems like /sys and /proc. The rationale for this is due to
the fact that the dentrys take up a lot of memory, and there's no reason to
have them if nobody is looking at them. Having a way to create them at the
time the user looks at/enters the directory would save quite a bit. But
there may be issues. What happens if there's no memory to allocate?

Our focus was on just working with the tracefs file system, but I would
like to discuss how we could make this into a generic feature that any
pseudo file system can use, and discuss what issues could arise by it, and
how to mitigate those issues.

Sorry, for the delay in posting. I understand that the deadline has just
passed, but starting a new job had caused me to not pay attention and I
missed it. Hopefully, you can still consider this.

-- Steve